<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>

	<style>
		div{
			position: relative;
		}

		#onKey{
			resize: none;
		}

		p{
			/* display: inline-block; */
			position: absolute;
			bottom: 0px;
			left: 165px;
		}

	</style>

</head>
<body>

	<div>
		<textarea name="" id="onKey" cols="30" rows="10" maxlength="100"></textarea>
		<p><span id="num">0</span>/100</p>

		<span class="abc"></span>
	</div>	
	
	<script src="../lib/jquery.min.js"></script>
	<script>
		var on = document.getElementById('onKey');
		var numm = document.getElementById('num');
		
		on.onkeyup = function() {
			var num = on.value.length;
			num > 100 ? num = 100 : num;
			numm.innerHTML = num;
		}

	
	</script>
</body>
</html>